Premiums for Indonesia's tyre grade SIR20 rubber soared to 22 US cents a kg versus Thai RSS3 grade from 5 cents in early October as weather disrupted tapping and Thai supply was plentiful, dealers said on Wednesday. SIR20 changed hands late on Tuesday at up to $1.73 a pound ($3.81 a kg) for December delivery, while RSS3 was traded at $3.59 a kg.
Supply constraints have pushed up the price of SIR20 above RSS3 for the first time in several years. Supply in Indonesia, the world's second-largest producer after Thailand, has been curbed by wintering in the southern part of the main growing island of Sumatra and the start of the rainy season in the northern part.